Arrgghh! I know how you feel...
1. I too have experiences with both MS and TM; but don't think that melt downs are directly caused by it. Rather, it seems that the collective effect of all stresses shortens one's fuse at times.
Stress is not a descriptive term that only relates to emotions; but also includes anything that requires the body and mind to adapt. This includes things like infections, excesses of temperature, environmental toxins, dysfunctions of the body systems, lack of sleep, over work, exercise, mental & emotional upsets, diseases etc.
To put things into perspective, I look at it this way:
Imagine that all of the effects of these stresses are stored in one expandable container and when that container is filled to capacity, the body system goes into survival mode (fight, flight or freeze).
When that happens, adrenalin is flowing as a protective mechanism which prepares the body for a fight, to flee or to freeze. If another stress is added at that time, it is like the straw that breaks the camel's back.
Because there is no room for the body to adapt to added stress at that point, the body goes into full on survival mode and the expressions of that are either fight (anger/rage), flight (retreating to somewhere secluded to hide...perhaps after slamming a few doors along the way) or freeze (shutting down of body systems and cognitive thought; as in shock).
When the fight, flight or freeze survival system gets turned on there is absolutely no tolerance for nonsense (which is another stress); just as there is little room for calm thought or critical thinking.
So what to do when one finds one's self in such a situation? If one can, it helps to consciously choose if it is more beneficial to fight, flee or freeze.
Fighting usually just leads to flight, and flight often leads to freezing; so in the end it is often most beneficial to calm down through intentionally going through the fight, flight or freeze stages in reverse order.
First, just stop (freeze). That means stopping what one is doing, and stopping all movement of the mind and the body to just breathe.
Second, remove one's self from the offending stress (flee).
Third, if calmly 'fleeing' in this way is not possible (as in when there is active infection, disease, pain etc), then out of compassion for the body and the mind, allow those aspects to deal with the main types of stresses quietly without adding others to it.
That usually takes one back to the conscious freeze phase to catch one's breath; and can include lying down for a bit and not thinking about all the other stresses.
When it comes to computer stuff though, it is often helpful to remind one's self at the outset that messing around with technology stuff is enough to test the patience of a turtle

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Thus, be well rested and have plenty of room for the abundant amount of stress that this can cause...and remember to freeze at the first hint of having reached the stress balloon's capacity.
2. Taking a little sugar or carbohydrate at the point when the stress balloon is about to burst seems to help in providing the necessary fuel for the fight, flight or freeze responses in a positive way, because low blood sugar is also a stress. Replenishing blood sugar to normal levels can shrink the stress balloon a bit.
Raising blood sugar beyond normal levels is also a stress so taking a lot of that sort of food can ignite the fight, flight or freeze survival responses like gasoline being thrown onto a small fire. Moderation with purpose and having a plan in mind of whether one is going to fight, flee or freeze is a beneficial way to incorporate satisfying that sugar craving.
Going out in public is not recommended for there are many potential stresses in such environments, never mind the added stress of more body and mind movements required just to get there.
Heaven help anyone who finds themself in the path of someone who is in any sort of survival mode. Road rage comes to mind

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Thus it is probably best to seek solitude and quiet until the body and mind have adjusted, calmed down and there is once again room for further adaptation to stress.
Hope that this helps but failing that, and keeping with the thought that the greatest of things are achieved in a light heart, a little levity might.
In the last 5 years I have intentionally thrashed 2 Apples, one Dell...and am considering Frisbeeing a new Microsoft lap top onto the driveway and driving over it several times with the truck if things don't start to synch very soon.
Sometimes enough is enough and you have to fight!
With love, Erika